The puzzle of the bee and the train

[Pedro]

@Princhester

You’re right, I see. I accept your correction that I adjusted my position to be a synthesis of both our positions.

That’s pretty funny. A “synthesis” huh? Who knew that’s what they’re calling it these days.

@Princhester

However, the fact is that right now you are saying that it is one thing and not the other, and you have no quantified data.

Appreciate the acknowledgement but I’m worried that you’re starting to sound a bit desperate, clinging to the “hard data” angle like a… bee to a train? (Awful pun, sorry). I didn’t catch your rigorous numerical proof when you answered the OP before. Is this it by any chance?

I don’t claim to know what happens quantitatively, only qualitatively. Besides an energy balance argument, it’s obviously not a trivial problem to model the elasticity of the collision accurately. That’s not what the OP asked. He asked whether the train stops relatively to the ground. If you can show any holes in my argument please do so. Otherwise I’m sorry I could not meet your outstanding scientific standards.

@Princhester

ISTM that it may be that as we move more and more towards the macro scale, the contact point on the larger object gets closer and closer to being stopped, but whether the surface actually stops depends on the atomic makeup of each object.

It may indeed, if we live in an alternate fantasy universe where physical law bends to your will.

@Princhester

Or could it perhaps depend upon the harmonics of the thing struck? When the bee hits it’s going to cause the front of the train to reverberate. What is going to affect the speed of vibration? Is that speed going to be higher or lower than the speed of the train?

It would reverberate farther upon impact than at any other time, since some energy is dissipated as heat. If the train surface doesn’t stop then, we can say for certain it never stops, relative to an external observer (it will always reverberate though, and stop relatively to the train’s frame of reference). Doesn’t prove anything but it allows us to exclude reverberation as a relevant phenomenon to answer the question posed by the OP.

[Princhester]

I’m not sure what your current position is. Let’s deal with this bit by bit. You’ve accepted that in a collision between a sufficiently heavy small object and a sufficiently elastic large one, the contact patch of the latter will stop. Do you now resile from that? Yes or no.

[Pedro]

@Princhester

I’m not sure what your current position is. Let’s deal with this bit by bit. You’ve accepted that in a collision between a sufficiently heavy small object and a sufficiently elastic large one, the contact patch of the latter will stop. Do you now resile from that? Yes or no.

No. I will try to recap as best as I can:

My main point is that it isn’t a paradox or inconsistent with the laws of physics for two bodies to collide, one reversing direction without the other one stopping. Here I am arguing against what you said on post #51. This becomes obvious when you realize there is action at a distance and doesn’t require further proof, I believe.

A secondary point is that, when there are flexible bodies involved (as all are) it is possible to have both situations. One, some part of the body with higher momentum effectively stops (e.g. trampoline against baseball) or two, no part of that body stops (e.g. bullet against person). I am also arguing that the bee-train example falls under the second scenario, without having proved so numerically.